If you think that you have found a security issue in Symfony, don't use the
bug tracker and don't publish it publicly. Instead, all security issues must
be sent to security [at] symfony.com. Emails sent to this address are
forwarded to the Symfony core-team private mailing-list.

As Symfony is used by many large Open-Source projects, we standardized the way
the Symfony security team collaborates on security issues with downstream
projects. The process works as follows:

After the Symfony security team has acknowledged a security issue, it
immediately sends an email to the downstream project security teams to
inform them of the issue;

The Symfony security team creates a private Git repository to ease the
collaboration on the issue and access to this repository is given to the
Symfony security team, to the Symfony contributors that are impacted by
the issue, and to one representative of each downstream projects;

All people with access to the private repository work on a solution to
solve the issue via pull requests, code reviews, and comments;

Once the fix is found, all involved projects collaborate to find the best
date for a joint release (there is no guarantee that all releases will
be at the same time but we will try hard to make them at about the same
time). When the issue is not known to be exploited in the wild, a period
of two weeks seems like a reasonable amount of time.

The list of downstream projects participating in this process is kept as small
as possible in order to better manage the flow of confidential information
prior to disclosure. As such, projects are included at the sole discretion of
the Symfony security team.

As of today, the following projects have validated this process and are part
of the downstream projects included in this process: